Synthesis, characterization and pharmacological activities of 5,6,11,12-tetrahydroindolo[2,3-alpha]carbazole derivatives.

A series of new 5,6,11,12-tetrahydroindolo[2,3-alpha]carbazole derivatives (3a-h) was synthesized. Treatment of 8-methyl-1-oxo-1,2,3,4-tetrahydrocarbazole (1a) with phenylhydrazine hydrochloride in ethanol furnished the title compound (3a) in poor yield along with 8-methyl-1-phenylhydrazono-1,2,3,4-tetrahydrocarbazole (2a). Better yields were obtained when 1a-h were treated with phenylhydrazine in glacial acetic acid. All the newly synthesized compounds were characterized on the basis of IR, NMR, mass-spectra and elemental analysis and screened for pharmacological activities.